(A) Field of the Invention
The present invention relates to an organic electroluminescence (EL) device, and particularly to an organic electroluminescence device of aromatic amine derivative.
(B) Description of the Related Art
Electroluminescence is a lighting phenomenon in which currents flow through a material or a material is disposed in high-voltage electrical fields. Electroluminescence is also known in industry as “cold light.” Electroluminescence devices may be zinc sulfide and blue diamond doped with copper or silver. Current development efforts in the electroluminescence field are focused on the application of organic materials.
Organic light-emitting diodes (OLED) with electroluminescence features use display technologies in which light is generated by current-driven organic semiconductor materials and lighting materials, so as to display images. In comparison with liquid crystal displays (LCD), the organic light-emitting diodes (OLED) have advantages such as light weight, thin profile (less than 1 mm), high brightness, large viewing angle (up to 170 degrees), no need for backlight, low power consumption, quick response, clear image display, low heat generation, vibration resistance, low manufacturing cost and bendability.
However, because electroluminescence devices do not have backlight units, they must include a self-contained light source. Therefore, the light efficiency of an electroluminescence device is quite important, and aggressive research is presently underway to develop improvements in such efficiency.
Japanese Patent JP3929337 (Pub. No. 2003-272863) discloses fluorescent compounds of aromatic amine derivative with green to yellow colors, of which the highest lighting efficiency is 6.5 cd/A. U.S. Pat. No. 6,815,090 discloses fluorescent compounds of aromatic amine derivative with yellow-green to red colors, of which the highest lighting efficiency is 6.7 cd/A.
The aromatic amine derivatives disclosed in U.S. Pat. No. 6,815,090 do not have sufficient lighting efficiency. For the application of passive matrix organic light-emitting diode (PMOLED) products, increased lighting efficiency is crucial to improving brightness and reducing the power consumption of products.